fix: add require condition to pi-tui exports for CJS resolution

createRequire() in shared/ui.ts uses CJS resolution which needs a
"require" condition in package.json exports. Without it, Node throws
ERR_PACKAGE_PATH_NOT_EXPORTED.

Verified locally: build, typecheck:extensions, test:unit (0 fail),
test:integration (0 fail), validate-pack all pass.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

packages/pi-tui/package.json

@@ -8,7 +8,8 @@
   "exports": {
     ".": {
       "types": "./dist/index.d.ts",
-      "import": "./dist/index.js"
+      "import": "./dist/index.js",
+      "require": "./dist/index.js"
     }
   },
   "scripts": {